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	$185.79	4.328%	$193.831	$193.83	$193.85	$193.80
Purchase #2	$142.31	12.547%	$160.1656	$160.17	$160.15	$160.20
Purchase #3	$56.90	3.303%	$58.7794	$58.78	$58.80	$58.80
Purchase #4	$170.56	8.203%	$184.551	$184.55	$184.55	$184.60
Purchase #5	$83.72	7.781%	$90.2343	$90.23	$90.25	$90.20
Purchase #6	$123.93	5.655%	$130.9382	$130.94	$130.95	$130.90
Purchase #7	$185.77	5.485%	$195.9595	$195.96	$195.95	$196.00
7 purchase totals =	$948.98		$1,014.4590	$1,014.46	$1,014.50	$1,014.50