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	$147.75	13.269%	$167.3549	$167.35	$167.35	$167.40
Purchase #2	$124.41	11.512%	$138.7321	$138.73	$138.75	$138.70
Purchase #3	$182.49	4.281%	$190.3024	$190.30	$190.30	$190.30
Purchase #4	$74.58	10.751%	$82.5981	$82.60	$82.60	$82.60
Purchase #5	$168.85	8.133%	$182.5826	$182.58	$182.60	$182.60
Purchase #6	$152.84	10.303%	$168.5871	$168.59	$168.60	$168.60
Purchase #7	$159.31	9.538%	$174.505	$174.51	$174.50	$174.50
7 purchase totals =	$1,010.23		$1,104.6622	$1,104.66	$1,104.70	$1,104.70