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	$145.79	4.284%	$152.0356	$152.04	$152.05	$152.00
Purchase #2	$42.57	10.294%	$46.9522	$46.95	$46.95	$47.00
Purchase #3	$109.81	7.549%	$118.0996	$118.10	$118.10	$118.10
Purchase #4	$146.96	4.359%	$153.366	$153.37	$153.35	$153.40
Purchase #5	$159.34	8.651%	$173.1245	$173.12	$173.10	$173.10
Purchase #6	$211.79	10.107%	$233.1956	$233.20	$233.20	$233.20
Purchase #7	$171.48	7.731%	$184.7371	$184.74	$184.75	$184.70
7 purchase totals =	$987.74		$1,061.5106	$1,061.52	$1,061.50	$1,061.50