Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$162.35	7.330%	$174.2503	$174.25	$174.25	$174.30
Purchase #2	$101.26	10.285%	$111.6746	$111.67	$111.65	$111.70
Purchase #3	$202.68	3.182%	$209.1293	$209.13	$209.15	$209.10
Purchase #4	$235.88	6.368%	$250.9008	$250.90	$250.90	$250.90
Purchase #5	$54.82	6.385%	$58.3203	$58.32	$58.30	$58.30
Purchase #6	$244.67	13.801%	$278.4369	$278.44	$278.45	$278.40
Purchase #7	$145.94	11.402%	$162.5801	$162.58	$162.60	$162.60
7 purchase totals =	$1,147.60		$1,245.2923	$1,245.29	$1,245.30	$1,245.30