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	$145.25	8.507%	$157.6064	$157.61	$157.60	$157.60
Purchase #2	$162.83	5.161%	$171.2337	$171.23	$171.25	$171.20
Purchase #3	$188.93	13.344%	$214.1408	$214.14	$214.15	$214.10
Purchase #4	$96.56	8.674%	$104.9356	$104.94	$104.95	$104.90
Purchase #5	$143.92	4.739%	$150.7404	$150.74	$150.75	$150.70
Purchase #6	$158.76	4.388%	$165.7264	$165.73	$165.75	$165.70
Purchase #7	$57.41	3.471%	$59.4027	$59.40	$59.40	$59.40
7 purchase totals =	$953.66		$1,023.7860	$1,023.79	$1,023.85	$1,023.60