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	$152.78	7.790%	$164.6816	$164.68	$164.70	$164.70
Purchase #2	$47.52	5.787%	$50.27	$50.27	$50.25	$50.30
Purchase #3	$192.94	3.229%	$199.17	$199.17	$199.15	$199.20
Purchase #4	$246.69	10.227%	$271.919	$271.92	$271.90	$271.90
Purchase #5	$232.30	4.653%	$243.1089	$243.11	$243.10	$243.10
Purchase #6	$152.62	13.739%	$173.5885	$173.59	$173.60	$173.60
Purchase #7	$91.96	11.215%	$102.2733	$102.27	$102.25	$102.30
7 purchase totals =	$1,116.81		$1,205.0113	$1,205.01	$1,204.95	$1,205.10