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	$233.71	7.460%	$251.1448	$251.14	$251.15	$251.10
Purchase #2	$224.64	7.345%	$241.1398	$241.14	$241.15	$241.10
Purchase #3	$186.72	7.201%	$200.1657	$200.17	$200.15	$200.20
Purchase #4	$94.41	6.810%	$100.8393	$100.84	$100.85	$100.80
Purchase #5	$101.46	5.380%	$106.9185	$106.92	$106.90	$106.90
Purchase #6	$33.93	4.641%	$35.5047	$35.50	$35.50	$35.50
Purchase #7	$90.29	9.483%	$98.8522	$98.85	$98.85	$98.90
7 purchase totals =	$965.16		$1,034.5650	$1,034.56	$1,034.55	$1,034.50