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	$161.72	12.438%	$181.8347	$181.83	$181.85	$181.80
Purchase #2	$244.74	4.384%	$255.4694	$255.47	$255.45	$255.50
Purchase #3	$196.85	10.461%	$217.4425	$217.44	$217.45	$217.40
Purchase #4	$250.33	4.380%	$261.2945	$261.29	$261.30	$261.30
Purchase #5	$81.90	12.166%	$91.864	$91.86	$91.85	$91.90
Purchase #6	$174.62	7.543%	$187.7916	$187.79	$187.80	$187.80
Purchase #7	$160.54	4.301%	$167.4448	$167.44	$167.45	$167.40
7 purchase totals =	$1,270.70		$1,363.1415	$1,363.12	$1,363.15	$1,363.10