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	$61.56	5.780%	$65.1182	$65.12	$65.10	$65.10
Purchase #2	$155.55	7.354%	$166.9891	$166.99	$167.00	$167.00
Purchase #3	$62.30	3.279%	$64.3428	$64.34	$64.35	$64.30
Purchase #4	$216.32	12.599%	$243.5742	$243.57	$243.55	$243.60
Purchase #5	$144.38	4.870%	$151.4113	$151.41	$151.40	$151.40
Purchase #6	$172.70	5.326%	$181.898	$181.90	$181.90	$181.90
Purchase #7	$160.93	12.716%	$181.3939	$181.39	$181.40	$181.40
7 purchase totals =	$973.74		$1,054.7275	$1,054.72	$1,054.70	$1,054.70