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	$223.86	4.153%	$233.1569	$233.16	$233.15	$233.20
Purchase #2	$153.28	13.868%	$174.5369	$174.54	$174.55	$174.50
Purchase #3	$88.85	12.250%	$99.7341	$99.73	$99.75	$99.70
Purchase #4	$64.69	12.576%	$72.8254	$72.83	$72.85	$72.80
Purchase #5	$221.92	3.814%	$230.384	$230.38	$230.40	$230.40
Purchase #6	$43.77	6.319%	$46.5358	$46.54	$46.55	$46.50
Purchase #7	$171.25	10.489%	$189.2124	$189.21	$189.20	$189.20
7 purchase totals =	$967.62		$1,046.3855	$1,046.39	$1,046.45	$1,046.30