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	$152.97	11.245%	$170.1715	$170.17	$170.15	$170.20
Purchase #2	$11.43	11.564%	$12.7518	$12.75	$12.75	$12.80
Purchase #3	$83.40	7.369%	$89.5457	$89.55	$89.55	$89.50
Purchase #4	$86.33	3.655%	$89.4854	$89.49	$89.50	$89.50
Purchase #5	$209.26	9.350%	$228.8258	$228.83	$228.85	$228.80
Purchase #6	$246.57	9.123%	$269.0646	$269.06	$269.05	$269.10
Purchase #7	$242.55	4.376%	$253.164	$253.16	$253.15	$253.20
7 purchase totals =	$1,032.51		$1,113.0088	$1,113.01	$1,113.00	$1,113.10