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	$200.93	7.216%	$215.4291	$215.43	$215.45	$215.40
Purchase #2	$146.37	4.113%	$152.3902	$152.39	$152.40	$152.40
Purchase #3	$89.42	7.818%	$96.4109	$96.41	$96.40	$96.40
Purchase #4	$140.58	11.170%	$156.2828	$156.28	$156.30	$156.30
Purchase #5	$135.34	7.467%	$145.4458	$145.45	$145.45	$145.40
Purchase #6	$131.45	13.746%	$149.5191	$149.52	$149.50	$149.50
Purchase #7	$104.44	3.411%	$108.0024	$108.00	$108.00	$108.00
7 purchase totals =	$948.53		$1,023.4803	$1,023.48	$1,023.50	$1,023.40