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	$144.32	7.702%	$155.4355	$155.44	$155.45	$155.40
Purchase #2	$130.68	9.459%	$143.041	$143.04	$143.05	$143.00
Purchase #3	$90.73	9.111%	$98.9964	$99.00	$99.00	$99.00
Purchase #4	$100.66	12.547%	$113.2898	$113.29	$113.30	$113.30
Purchase #5	$148.57	13.665%	$168.8721	$168.87	$168.85	$168.90
Purchase #6	$152.36	13.177%	$172.4365	$172.44	$172.45	$172.40
Purchase #7	$174.87	11.532%	$195.036	$195.04	$195.05	$195.00
7 purchase totals =	$942.19		$1,047.1073	$1,047.12	$1,047.15	$1,047.00