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	$168.56	3.588%	$174.6079	$174.61	$174.60	$174.60
Purchase #2	$121.73	4.599%	$127.3284	$127.33	$127.35	$127.30
Purchase #3	$83.50	8.629%	$90.7052	$90.71	$90.70	$90.70
Purchase #4	$169.69	3.312%	$175.3101	$175.31	$175.30	$175.30
Purchase #5	$208.77	3.117%	$215.2774	$215.28	$215.30	$215.30
Purchase #6	$34.78	4.498%	$36.3444	$36.34	$36.35	$36.30
Purchase #7	$167.25	8.677%	$181.7623	$181.76	$181.75	$181.80
7 purchase totals =	$954.28		$1,001.3357	$1,001.34	$1,001.35	$1,001.30