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	$94.63	3.698%	$98.1294	$98.13	$98.15	$98.10
Purchase #2	$183.98	13.655%	$209.1025	$209.10	$209.10	$209.10
Purchase #3	$82.50	5.412%	$86.9649	$86.96	$86.95	$87.00
Purchase #4	$62.70	6.417%	$66.7235	$66.72	$66.70	$66.70
Purchase #5	$168.57	12.132%	$189.0209	$189.02	$189.00	$189.00
Purchase #6	$231.44	9.773%	$254.0586	$254.06	$254.05	$254.10
Purchase #7	$184.77	3.852%	$191.8873	$191.89	$191.90	$191.90
7 purchase totals =	$1,008.59		$1,095.8871	$1,095.88	$1,095.85	$1,095.90